The present invention generally relates to the use of lasers in construction and other fields.
Level and plumb references are often needed in construction and other fields, and are traditionally determined with spirit levels. For long distances, auto levels and water levels have traditionally been used. More recently, these tasks are now being done with laser products. Automatically leveling laser products are preferred for their ease of set up and use.
The most common type of laser level device generates a spinning beam of laser light. A beam of light emanating from the device produces a spot on an impinged surface. But if the beam is swept, the eye perceives a line on the surface. A line is generated on any flat surface anywhere in the plane of the light. To increase the brightness on a surface, the beam my be tightly dithered back and forth in one angular range. Such devices may be manually or automatically leveled.
Increasingly common are line generators, which use a cylindrical lens or other element to generate a plane of laser light. The angular spread of light may be 90 degrees or more. Multiple fans may be aligned in a common plane to generate a full 360 degree plane of light. When this plane of light impinges on a surface, a sharp line is visible.
In generally all of these devices, the laser is offset from the base of the unit, and the laser unit can be adjusted in height using shims or a costly elevating stage. Most often, the offset value is determined and compensated for as needed. For example, to determine the correct vertical position for installing a new countertop at another location in a room, a self leveling pointing device can be placed on an existing counter top and positioned to shoot across a room. The offset of the beam up from the counter top is determined, and the beam is positioned to hit the wall where needed. A mark is then made on the wall at the beam, and the offset below the beam can then be measured to mark the true position of the new counter top.
The offset value must be explicitly handled in each case. For example, to level a countertop, a pointer device can be placed in one corner of it. The height of the beam near the unit is noted on a target or a tape measure as the target. Then the target is moved to a far corner and the target is moved back and forth to find the beam. The height is measured on the target at the new position. The difference between the two readings is the error in level of the counter. If the counter top is bowed, multiple readings must be taken. During the tedious process of shimming, the readings must be repeated at multiple points and in multiple directions and or along several axes. A similar process can be used with line generators and spinning lasers.
As a further example, the flatness of a surface can be checked by positioning a laser beam or plane next to a surface. Multiple height or offset measurements can be made at various points covering the surface, which is a tedious and error prone process.